Ignition system safety switch



March 25, 1958 A. DAVIDSON IGNITION SYSTEM SAFETY swITcH 2 Sheets-Sheet 1 Filed Feb. 15, 1956 INVENTOR n O 3 Z w ,H m a 5 w. 1 E 6 M 7m M V 5 I O s a n Q m A w W 0 3/ T A m w March 25, 1958 A. DAVIDSON IGNITION SYSTEM SAFETY SWITCH Filed Feb. 13, 1956 2 Sheets-Sheet 2 I N VEN TOR JY'r'noZaZ ,Da vidson ATTORNEY United States Patent 2,823,382 IGNITION SYSTEM SAFETY SWITCH ArnoldDavidson, Lo's' Angel'es, Calif. Application February 13 .1956, Serial No.-565,149=

2 Claims; (Cl. 200 97) This "invention relates to a-safety switch for the ignition system of an engine and while primarily adaptedfor use in the ignition system of a motorvehicle engine, isequally well'adapted for use with the ignition systems of other engines.

It is a primary object of the present invention to-provide a safety switch which will function automatically to de-energize the ignition systemand electrical accessories such as the lights, horn, radio andheater and similar electrical devices when theengine is not in operation-or when the engine is left idling for a predetermined period of time.

More particularly, it is an'objectof the-presentinvention to provide a-novel switch which will effectively function to shut off an engine whichis inadvertently left running at an idling speed at the same time that, the switchdisconnects the electrical accessories associated with the-vehicle,-.to thus provide a safety; switch which will not only eliminate the discharging ofa: battery: due to electrically energized-parts being left=energized but which will additionally preventpossibleloss of life/due to carbon monoxide gases and-which'frequently. occurs where vehicle engines are left-operating.

Various other objects and-advantages-ofthe invention will hereinafter become more fully apparent from the followingdescription of the drawings, illustratingfa presently preferred embodiment thereof, and whereinz:

Figure l is a side elevationalview of the safety" switch;

Figure 2 is'a longitudinal sectional view thereof, taken substantially along a plane as indicated bythe linelw-Z of Figure 1;.

Figure 3 is a dia'grammatic view of a part of anengine ignition system showing the safety switchinterposed therein; 2

Figure 4 is a top plan view, partly in-section, of-the safety switch, and

Figure 5 is a fragmentary. vertical sectional view on an enlarged scale of a portion ofthe safety switch and showing adifi'erent-position of certainof the partsthereof from the positionsofisaid parts as seen inFigure 2.

Referringimore specifically to the drawings, the-safety switch in its entirety and comprising the invention is designated generally 7 and includes a substantially flat base member or panel 8 which isformed of electrical insulating. material and which is adapted to be secured to any suitable supporting.surface 9,:as for example the forward side of the fire wall of a motor vehicle.

The base or panel 8 is of elongated shape and an electromagnet,designated generally 10, is suitably secured to anouter side or face ofsaid base 8 and intermediate of the ends thereof. The electromagnet 10 includes an inner windingv 11 and an outer winding 12'. The ends of the windings 11 and 12 are disposed between a=disklike head 1'3 and'anannular endmember' 14. Said members 13 and 14- are formed of electrical conducting ma terial. A guide sleeve 1'5 has an end portion-extending through the open center of the end-member 14 and through the inner winding 11 and which terminates in anopenend' 16 into which extends acentral boss 17- of the head 13. The guide sleeve 15 is likewise formed of anelectrical conducting material. The electromagnet 10also' includes a core 18, formed of soft iron ora similar material, which is slidably disposed in-the bore 19 of the sleeve 15. The cor-e18 has athreaded-recess 20 opening outwardly of an inner endthereof in which is threadedly secured'an end of a stem 21, which projects f'rom'said core end'slidably. through a centralopening22 ofthe central portion'17 of the head 13.

Beyond the head-13,.the stem 21 is providedv withan end part 23 of-reduced diameter on which is-mounted a disk or washer'24, forming/a springstop and which seats against the shoulder 25 of the stem-21 formed-by the restricted stem portion 23; The stem portion- 23, beyondthe spring, stop 24, extendsslidably through a central'o'pening 26 of a disk or washer 27 which forms an electrical conductor bridge. A coiled compression spring 28' is disposed between the spring stop 24 and the bridge 27 A pair ofspaced electrical contacts 29 and'30 are suitably secured toand project outwardly from said aforementioned side of'the base 8, adjacent one end thereof. The contacts 29 and 30 are disposed beyond the bridge 27 andin transverse alignment relative to one another. Said-contacts 29 and30 are electricallyconnected to spaced contact posts 29a and 30a, respectively, by elec trical conductor wires 2% and 3i)b,.respectively.- The posts 29a and 30a are-likewise secured to and project from said side of the base 8'. A pair of brackets31-are suitably secured to said base side, laterally. outward-with respect to the contacts'29 and 30. The brackets 31 support-a-pair of'leaf'springs 32 having inwardly extending free ends which bear against the side-of the bridge 27, disposed remote-from the spring. 28,. and which normally urge the conductor bridge 27'towardthe electromagnet 10 and out ofengagement with the contacts 29 and 30.-

As best seen in Figures-2 and. 5, the bore 19 doesanot extend to the other end ofthe sleeve 15 so that said sleeveincludes an end portion 33, disposed-remote-from theelectromagnet 10,; which has a restricted port 34 opening into the bore 19 and having an: opposite'end communicating with the restrictedend of: a'frusto-conical valve seat 35. The opposite end of'. the valve seat 35 opens into a chamber 36 which is providedwith-one or more restricted ports 37 which open-laterally outwardly of the part 33; The-chamber 36 may be formed in the part 33in any suitable manner as by a: cut madelaterally into said pa'rt, after whichthe chamber 36.can be'closed except for its-connection with the valve seat 35' and a threaded bore 38. The ports 37 can then be drilled. The bore 38 is internally threaded and communicates with the chamber 36 and alignswith-the-valve-seat35. A needle valve 39 is threadedinwardly throughthe bore 38 and-has an unthreaded conical inner end 40 which extends into the valve seat 35 and which is adjustable relative thereto and normally disposed so that a slight clearance exists between the wall of the valve seat 35 and the conical needle valve end 40, as seen in Figures 2 and 5. A jamb nut 41 is preferably threaded on the outer end of the needle valve 39 and abuts against the outer'end of the portion 33 to maintain t'he-necdle valve in selected adjusted positions A bore-42 extends longitudinally through theco're18 and has an enlarged threaded end 43 dispos'edre'mote from the recess 20. The core 18' is alsop'rovided with one or more lateral passages 44 which open laterally outwardly thereof and into the bore 42, adjacent the inner end of the core whichis provided with the recess 20i A relatively thick rigid-disk 45 is disposed in the bore 19 beyond the outer end ofthe core 18 and is connected to the core by aheaded screw 46 which exte nds loosely through the retaining member 45 and threaded engages in the threaded bore end 43. A sealing member or washer 47, formed of felt or the like, is disposed between the retaining member 45 and the outer end of the core 18 and is clamped between said parts by tightening of the screw 46, which extends centrally through the sealing member 47. The sealing member 47 is slightly larger in diameter than the core 18 and retaining member 45 so that its periphery has a close fitting working engagement with the wall of the bore 19, as seen in Figures 2 and 5.

As best seen in Figure 5, the screw 46 extends loosely through a central opening 48 of the retaining member 45. Said opening 48 has an enlarged outer end 49 in which the head of the screw 46 is countersunk. The screw 46 has a bore 50 extending longitudinally therethrough the inner end of which communicates with the bore 42 and the outer end of which communicates with the bore 19 adjacent the port 34. A flap valve 51, which is preferably substantially disk shaped, is secured adjacent a peripheral portion thereof by a screw 52 to the outer face of the retaining member 45. The flap valve 51 normally assumes a position against the outer face of the retaining member 45 to seal the outer end of the opening 49 and the outer end of the bore 50. However. said flap valve 51 is capable of flexing away from the retaining member 45 to an open position as illustrated in Figure from its normal position of Figure 2.

A cylindrical housing member 53, of electrical insulating material, may surround the outer winding 12 of the electromagnet 10. A pair of contact posts 54 and 55 are secured to and project from the front face of the base 8, preferably at one side of the electromagnet 10, and are connected to the outer winding 12 by conductor wires 54a and 55a, respectively, which extend through the housing member 53. A similar pair of contact posts 56 and 57 are mounted on the front face of the base 8, preferably at the opposite side of the electromagnet 10, and are connected to the inner winding 11 by conductor wires 56a and 5711, respectively, which extend through openings 56:) and 57b, respectively, formed in the members 13 and 14, as seen in Figure 2.

For the purpose of illustrating a preferred application and use of the safety switch 7, said switch has been illustrated in Figure 3 in a portion of an ignition circuit of a motor vehicle, only a part of which has been shown. The ignition circuit portion as illustrated includes a storage battery 58 which is grounded in the conventional manner as at 59 to the vehicle frame. A conductor 61 leads from the other terminal of the battery 58 to a contact post 61 of the electric starter and thence to the contact post 54. The starter switch or button 62 is suitably interposed in the conductor wire 60. The contact post 55 is grounded to the vehicle frame, as seen at 59, as is also the contact post 57. Conductor wires 63 and 64 connect the posts of the ignition system generator 65 to the posts F and A, respectively, of a conventional voltage regulator 66. The conductor wire 64 continues on from the voltage regulator post A and is connected to the contact post 56. A conductor wire 67 leads from the contact post B of the voltage regulator to the contact post 29a and is thus connected to the switch contact 29. A conductor 63, which is connected to the contact post 36a and thus to the switch contact 38, extends through the vehicle amrneter 69 and ignition switch 70 and to thegrounded ignition coil 71, and has a branch conductor 72 leading to various electrical accessories of the vehicle, not shown, such as the lights, horn, radio and heater, each of which is likewise grounded to the vehicle frame.

The spring 28 will normally hold the core 18 in its position of Figure 2 and the leaf springs 32 will maintain the conductor bridge 27 out of engagement with the switch contacts 29 and 34) when the spring 28 is thus substantially unloaded, so that the electrical connection will be broken between the conductor wires 67 and 68 to prevent current being supplied to the ignition, ignition coil .orthe 4 electrical accessories. Accordingly, these elements cannot drain current from the storage battery 58.

To start an engine to which the ignition system is connected, the ignition switch 70 is initially closed even though no current is being supplied thereto and to the ignition coil. The starter button or switch 62 is then closed to supply current to the starter. As the wire 60 which supplies currentto the starter from the battery 58 is grounded through the post 54, outer winding 12 and post 55, when the starter motor is energized, the outer winding 12 of the electromagnet Will also be energized and the core 18 will be drawn toward the head 13 and within the bore of the guide sleeve 15, which is formed of an electrical conducting material. The stem 21, 23 will move upwardly with the core 18, as seen in Figure 2, carrying with it the spring stop 24. The spring 28 will be compressed between the stop 24 and bridge 27 sufficiently to overcome the strength of the leaf springs .32 so that the loaded spring 28 will force the bridge 27 against the contacts 29 and 30 to supply current to the vehicle ignition and electrical accessories through the conductor wires 68 and 72. During this upward movement of the core 18, air in the bore 19 between the core 18 and head 13 will enter the core bore 42 through the passages 44 and will pass through the bore 50 to unseat the flap valve 51, as illustrated in Figure 5, to vent the chamber of the bore located between the core 18 and the part 33, so that upward movement of the core 18 when the electromagnet 10 is energized will not be impeded to enable the bridge 27 to promptly form an electrical connection between the 'contacts 29 and 30. Sutficient clearance also exists between the bore 22 and stem 21 for venting the portion of the bore 19 located between the head 13 and core 18. The winding 12 may be of heavier wire than the winding 11 to insure that the core 18 will be magnetized when current is passed through the winding 12 by closing of the starter switch 62.

Upon starting of the engine and opening of the starter switch 62, electric current will be supplied from the generator 65 through the wire 56 to the inner Winding 11 to maintain the core 18 magnetized to hold the bridge 27 in engagement with the contacts 29 and 36. The flap valve 51 will return to its closed position as seen in Figure 2 when the core 18 has ceased to move toward the head 13. Accordingly, if the engine is permitted to idle so that the generator 65 does not charge, the loaded spring 28 will tend to force the stem 21, 23 and the core 18 downwardly as seen in Figure 2. However, the closed valve 51 will prevent air from escaping from beneath the core 18 to above said core in the bore 19, through the bores 50 and 42, and the sealing washer 47 will prevent air escaping through the bore 19 around the core 18. Accordingly, the parts as shown in the bottom of Figure 2 and in Figure 5 function as a dashpot to effectively regulate the speed of movement of the core 18 away from the head 13, governed by the rate of escape of air from beneath the core 18 between the valve seat 35 and the needle valve end 48. Thus, a suflicient period of time will elapse after the core 18 is demagnetized before the spring 28 can become sufiiciently unloaded to permit the leaf springs 32 to disengage the bridge 27 from the contacts 29 and 30. This time interval can be varied by adjustment of the valve end 4t) relative to the valve seat 35 so that a normal idling period of a vehicle -engine, as for example when stopping in traflic, will not result; in disconnecting the ignition system and electrical accessories from the storagebattery; However, if the vehicle engine is inadvertently left idling, the operation thereof will be stopped after a reasonable period of time by re turn of the core 18 to its position of Figure 2. Thus, the possibilty of a person being killed by carbon monoxide gases from an engine is eliminated. Additionally, it will be apparent that when the engine is shut off by opening of the ignition switch 70, that the'electrical accessories will be disconnectedfrom the storage battery after the normal period of time required for the parts to resume their positions of Figure 2. This will likewise occur if operation of the engine is interrupted without opening of the ignition switch.

Various modifications and changes are contemplated and may obviously be resorted to, without departing from the spirit or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. A safety switch of the character described comprising an electromagnet, a pair of electrical contacts, means supporting said contacts in spaced apart electrically insulated relation to one another and to the electromagnet and in a position toward which the core of the electromagnet is movable when magnetized, a bridge member of electrical conducting material, means connecting said bridge member to said core for movement of the bridge member into engagement with said electrical contacts when the core is magnetized, said means connecting the core to the conductor bridge comprising a stem connected to and projecting from the core toward said spaced contacts and extending slidably through said conductor bridge, a spring stop secured to said stem between the core and conductor bridge, and a compression spring interposed between the conductor bridge and spring stop and loaded by movement of the spring stop toward said spaced contacts for displacing the conductor bridge into engagement with the contacts when the core is magnetized and for displacing the core away from said spaced contacts, when the core is demagnetized, and spring means bearing against said conductor bridge for moving the con 6 ductor bridge out of engagement with the spaced contacts when the tension on the compression spring is diminished by movement of the demagnetized core away from said contacts.

2. A safety switch as in claim 1, a dashpot for retarding movement of the demagnetized core under the biasing action of the compression spring, said dashpot including a sleeve having a bore in which the core is slidably disposed, said sleeve having a restricted port opening to the atmosphere at an end of the sleeve disposed remote from said spaced contacts, a manually actuated valve regulating said port, sealing means carried by the core and engaging the wall of said bore to prevent the escape of air through the bore around the core, said core having an air passage extending therethrough and opening into the bore on opposite sides of said sealing means, and a check valve associated with said air passage and carried by the core to permit air to pass freely through the core and into the bore adjacent said restricted port and valve and preventing the passage of air through said passage in the opposite direction.

References Cited in the file of this patent UNITED STATES PATENTS 803,486 Hill Oct. 31, 1905 888,340 Macloskie May 19, 1908 1,071,886 Cubitt Sept. 2, 1913 1,088,268 Fagerlund Feb. 24, 1914 1,532,003 Traver Mar. 31, 1925 2,021,822 Whitney Nov. 19, 1935 2,158,428 Robertson May 16, 1939 

